It is often necessary to position one member with respect to another at a given angle and to maintain such orientation. Numerous applications, spanning diverse fields of technology exist for such an arrangement. For example, position retaining mechanisms are used in lighting fixtures associated with work stations and drafting boards. Also, they are used in document holders for word processors, printed circuit board jigs for component assembly and inspection, camera tripods, and automobile rearview mirrors.
Present day adjustable position retaining devices generally utilize a ball and socket assembly in which the adjustment of the members coupled respectively thereto and their retention is a function of frictional forces. In some cases, the socket has a split configuration and pressure applied thereto by a screw tightened at high torque levels brings the socket surface into closer contact with the ball. It is apparent that any desired orientation of the members must overcome the friction between contiguous surfaces of the ball and socket which tends to resist such motion. After repeated reorientation of the members, wear and material fatigue require that additional pressure be applied to the socket in order to retain a selected member orientation, particularly when one of the members is supporting a substantial load. Ultimately, regardless of the torque applied to the pressure screw, no further increase in the frictional forces are possible, and the desired angular position of the members cannot be maintained.
In view of the universality of position retaining mechanisms, the need exists for a device which will permit repetitive changes in angular position with minimal pressure on the assembly parts. Moreover, the selected position should be capable of being held indefinitely and not be dependent upon frictional forces. The mechanism of the present invention fills such a need.